Question

In an atom, the total number of electrons with quantum numbers $n=4,l=2ands=+\frac{1}{2}$ are :

• A.
  10
• B.
  5
• C.
  7
• D.
  14

Answer 1

The correct option is B

5
$n=4,l=2ands=+\frac{1}{2}$
The above quantum numbers is the description of 4d subshell with spin $s=+\frac{1}{2}$.

Number of orbitals in a d subshell with l = 2 is $2l+1$ = $2\times 2+1$ = 5.

Total number of electrons possible since each orbital can have maximum of 2 electrons is 10.
The number of electrons with spin quantum number $s=+\frac{1}{2}$ are 5
The other 5 electrons will have the spin quantum number $s=-\frac{1}{2}$